Use java_aconfig_library for nearby and thread flags

Connectivity repo now can use java_aconfig_library since this target is
available on all downstream branches.

Bug: 345121279
Test: TH
Change-Id: I6d267ddac89731a8efbef2ee98a3baa1df754ff5
diff --git a/common/thread_flags.aconfig b/common/thread_flags.aconfig
index 43acd1b..0edb7a8 100644
--- a/common/thread_flags.aconfig
+++ b/common/thread_flags.aconfig
@@ -8,3 +8,11 @@
     description: "Controls whether the Android Thread feature is enabled"
     bug: "301473012"
 }
+
+flag {
+    name: "configuration_enabled"
+    is_exported: true
+    namespace: "thread_network"
+    description: "Controls whether the Android Thread configuration is enabled"
+    bug: "342519412"
+}
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